Harbaugh leveled the accusation on "The Waddle & Silvy Show" on Chicago's WMVP-AM.
"I'm not buying a 'mistake' thing," Harbaugh said, via the Chicago Tribune. "They knew what they were doing."
The Bears told the Ravens they would trade their 29th overall pick and a fourth-round selection (127th overall) for the 26th pick to ensure they landed offensive lineman Gabe Carimi. The deal fell through when the Bears failed to contact the league to consummate the deal, and the Ravens were moved back one slot because time ran out on their pick. That enraged the Ravens, who demanded compensation.
"They agreed to (trade) a pick," Harbaugh said. "They got their guy (Carimi) on the phone. They recognized he wasn't getting calls from the team behind them (the Chiefs). And then they basically stalled for over a minute, telling us that they had called the trade in. So that was just not honest.
"They hadn't called the trade in. They said it was a mistake; those guys have been doing this for a long time, c'mon. You communicate back and forth, and someone is responsible for calling the trade in. There's no way not to get that done."
The end result almost seemed secondary to Harbaugh, whose team doesn't play the Bears this season.
"That's not OK. It's not ethical, it's not right," the coach said. "We basically took them at their word, and obviously that was a mistake."